Construction of a 21-Membered-Ring Orifice on [60]Fullerene

Open-[60]fullerenes possessing a huge orifice with a ring-atom count exceeding 19 have been confined to only a few examples. Herein, we report a 20-membered-ring orifice which enables for a guest molecule such as H₂ , N₂ , and CH₃ OH to be encapsulated inside the [60]fullerene cavity. In addition, a 21-membered-ring orifice was prepared via a reductive decarbonylation, in which one of the carbon atoms was moved out of the [60]fullerene skeleton as an N,N-dimethylamide group. At a low temperature of -30 °C, an Ar atom was encapsulated with an occupation level up to 52 %. At around room temperature, the amide group on the orifice rotates along with the C(amide)-C(fullerene) bond axis, realizing a self-inclusion of the methyl substituent on the amide group as confirmed NMR spectroscopically and computationally.